Toss the lamb with the flour, 1 teaspoon of sea salt, and pepper, coating all sides.

Heat a large Dutch oven (or heavy-bottomed stock pot) over medium-heat, and pour in the olive oil.

When the oil is hot, and working in batches as necessary, brown the meat on all sides (about 8 to 10 minutes). Remove and set aside.

Add the red onion to the pot, and cook until the onions are golden brown (5 minutes).

Stir in the tomatoes, garlic, and cilantro stems, and season with a pinch of sea salt. Cook, stirring often, for 4 to 5 minutes.

Pour in the stock, add the browned meat back to the pot, then stir in the garam masala and remaining teaspoon of sea salt. Bring to a boil, then reduce the heat to medium-low and simmer for 45 minutes to 1 hour, until the stew has thickened and the meat is tender.

Taste and adjust seasonings as necessary, then stir in the cilantro leaves and lemon juice.